Resistance element



"T. F. BAILY AND F. T. COPE.

RESISTANCE ELEMENT.

' APPLICATION FILED APR.3, 1919.

1,372,830. E E Patnted Mar. 22,

J, INVEN 70/?6} Thaddeus 1'15 aiZy 549 Frank 7. Copa,

ayawws wgrw UNITED STATES PATENT OFFICE.

THADDEUS r. BAILY ANn FRANK 1*. corn, or ALLIANCE, onro, ASSIGNORS TOTHE ELECTRIC FURNACE comrANz-or ALLIANCE, 01110, A ConronA'rIoN or01110.

RESISTANCE ELEMENT.

Specification of Letters Patent. I Patented 1131', 22,1921,

Application filed April 3, 1919. Serial N6. 287,280.

To all whom it may concern Be it known that we, THADDEUs BA ILY andFRANK T. Corn, citizens of the United States, both residing atAlliance," in the county of Stark and State of Ohio, have invented a newand useful Resistance Element, of which the following is a specificatheappended claims, it

tion. 7

This invention relates to resistance elements for electric furnaces, theobject being to construct a resistance element of a material of highconductivity, inclosed within material of low conductivity, the saidmaterial of high conductivity being sealed .within the material of lowconductivityand being designed to function nrim'arilv as a heatingelement to raise the temperature of the material of low conductivity tothereby increase the conductive efiioiency of the material of lowconductivity.

With this and other objects 111 view the invention consists in the novelconstruction and arrangement of parts, hereinafter de-.

scribed, illustrated in the accompanying drawings, and particularl eingunderstood that various changes in the form, .proportions, size andminor details of construc- 3 tion may be made within the scope 'oftheappended claims, without departmg -from the spirit or sacrificing any ofthe advantages ofthe invention. In the drawings: Figure l is atransverse section through an electric furnace of the resistance typeshowin our improved resistance element in position within the heatingchamber. I

Fig. 2 is a cross section through, a resistance element constructed inaccordance with our invention, said element being made in tubular form.

tion of one of our improved resistance elements.

1 Similar numerals of; reference indicate corresponding parts throughoutthe several figures of the drawing.

In electrlcal furnaces of the kind known as the granular 'ca'rbonresistance type, the

material of an extremely high fusing point,

fill the said trough with particles of cracked carbon or similarmaterialand place elecpointed out in oxidation ,as ,well as otherobjections are found to this type of element, but because of the factthat a material of high conductivity must be used to create theheat,this type of element continues to be used.

In our device we aim to obviate the obj ections which exist in the nowknown types of elements. The outer portion 1 of our resistance elementis preferably formed of carborundum which is a material of very I highfusing temperature, but of low electricalconductivity at atmospherictemperature. l he element is placed within the heating chamber 2 in theordinary way and may be formed,as shown in Fig. 2, of a single solidpiece of carborundum with an aperture 3 extending longitudinally-throughits center portion. This aperture or bore is relatively small incomparison with the diameter of the carborundum portion of the element'Cracked carbon, shown at 4 or other suitable material ispacked withinthe bore and the usual electrodes 5 are then inserted to form a sealedjoint at each end, no air being permitted tocontact with the particlesof carbon. When the current is turned on it will readily flow from oneof the electrodes 5 through the cracked carbon to the other. electrode,since the carbon is a material'of low conductivity, but little cur-3rent will flow through the carborundum portion of the element until thetemperature of i I the said carborundum has been raised to a Fig. 3 is afragmentary yiew showing a longitudinal section through an endjpor--high point due to'fthe' heating of'the carbon. When, however, thetemperature of the carborundum has begunto rise, itsconductivitywillalso rise and upon reaching a high temperature, thecarborundum itsel becomes a conductor and the current .will flow freelythrough the carborundum portion of the element. I The cracked carbonbeing sealed within'the carborundum portion of the element cannot belost through oxidating and since the carborundum itself I does not'beginto oxidate until it reaches a temperature considerably higher than anyworking temperature needed within the fur- I we claim as new and insections and fitted together to" give any 'outside contour withoutchanging the pr1n-' 10 ciple of the invention.

Having fully described our invention what Letters Patent, is' I 1. Aresistance element comprising an outer portion formed of material of lowelectrical conductivity and having a bore therethrough, and a materialof high electrical conductivity within said bore.

2. A resistance element having a hollow' portion formed of a material oflow electrical conductivity, said hollow portion be ing filled with amaterial of high electrical conductivity;

3. A resistance element composed of a portion formed of material ofrelatively low electrical conductivity and a portion formed of materialof relatively high electrical conductivity, the material of highconductivity being sealed within the material of low conductiv-ity andelectrodes in contact with the material of high conductivity.

4. A resistance element'formed of material of low electricalconductivity with an aperture extending lengthwise of said eledesire tosecure by ment, a'material oi highelectrical conductivity filling saidaperture and electrodes in contact with said material of highconductivity said material of high conductivity being sealed within thematerial of low conductivity;

5. A resistance elementformed of carborundum or like material and havingan aperture extending lengthwise therethrough,

cracked carbon or like material filling said aperture and sealedtherein. "t '6. A heating element which carries our rent at a hightemperature and a resistance element within said heating element tobring the temperature of the heating element to the point where itwill-carry; current.

7'; A heatingelement which normally at low temperature is afp'oor'electrical con-- du'ctor and a resistance element embedded within theheating element to bring the tem-' perature of .the heating element to apoint where it will carry current.

8. A primary conductor comprising a jacket of material having a highelectrical resistance at low or normal temperatures and a secondaryresistance contained within.

said jacket for heating the jacket to a point where the major portion ofthe electricity will flow through thejacket;

/ In testimony that we claim the above, we

have hereunto subscribed our names.

' .THADDEUS EBA/1L1 --FRANK 1. COPE.

